This application generally relates to image processing, and more particularly, correcting frame-to-frame image changes due to motion for three dimensional (3-D) persistent observations.
There is a desire to collect persistent video (i.e., multiple image sequences) of a target from overhead platform-based (e.g., airborne or space-based) sensors that can easily be viewed, and/or interpreted, via displays. This may be especially important for military personnel and/or for other persons, using portable devices that may have limited processing capabilities. Conventional persistent video sensors generally stay fixed to (or focus on) a single point, for instance, on the ground, while the overhead platform is in motion. The motion of the platform, however, causes changes in scale, perspective (e.g. parallax), rotation, and/or other changes in viewing geometry. These changes can complicate or prevent human and/or machine interpretation of targets, features, and threats.
Conventional persistent video relies on human interpretation to ignore changes in the measured scene that result from platform motion.
Stereo photogrammetric systems generally collect two disparate views of a scene and heavily process them to create 3-D maps. For instance, overhead scanning sensors may collect multiple images that are processed to estimate 3-D features in the images. Error in conventional height estimates are large, though, typically a multiple of the ground sample distance (“GSD”) of the sensor. U.S. patent application Ser. No. 12/425,188, filed Apr. 16, 2009, and herein incorporated by reference in its entirety, discloses a self-correcting adaptive long-stare electro-optical system (“SCALES”) that is configured to calculate transformations to prevent image intra-frame distortion caused by a relative motion between the scene and the imaging platform and to prevent geometric differences from manifesting as smear within an integration time, thus preventing intra-frame distortion. However, this system relies upon controlling an optical element based on the transformation to prevent the image distortion, and may require more computations for intra-frame motion prevention.
An imaging platform having improved image quality thus is desired without the aforementioned drawbacks. For example, an imaging platform is desired which can correct frame-to-frame image changes caused by relative motion between the imaging platform and the scene. Further, an imaging platform is desired which can enhance the quality of captured images in applications which are particularly susceptible to inter-frame changes, e.g., imaging platforms having a wide field of view and/or high angular rates of movement with respect to the ground, especially for three-dimensional features in the scene.